1. Field of the Invention
The present invention relates to a wire-connecting device, in particular, the wire-connecting device having a joint terminal for electrically connecting an inner conductor of a coaxial cable to core wire of an electric wire.
2. Description of the Related Art
FIG. 6 is a partially perspective view of a conventional wire-connecting device. FIG. 7 is an exploded perspective view of the wire-connecting device in FIG. 6. As shown in FIGS. 6 and 7, the wire-connecting device 100 includes a coaxial cable 110, a lead wire 120, a crimp contact 130, an earth plate 140, a shell 150, an insulator 160.
The coaxial cable 110 is, for example, a cable for connecting an antenna mounted on a vehicle. The coaxial cable 110 includes, as well-known, an inner conductor 111, a braided wire 112 surrounding the conductor 111, an insulator 113 interposed between the conductor 111 and the braided wire 112 and made of such as polyethylene, and a coating 114 surrounding the braided wire 112 and made of such as synthetic resin.
The lead wire 120 includes a plurality of core wire 121 made of copper, aluminum, or the like, and an insulator 122 covering the core wire 121. The crimp contact 130 is formed of a metallic hollow cylinder. In the cylinder, the inner conductor 111 of the coaxial cable 110 and the core wire 121 of the lead wire 120 are face to face and crimped together so that the inner conductor 111 and the core wire 121 are electrically connected to each other.
The earth plate 140 includes a substantially square-shaped fixed plate 141 formed by, for example, pressing a conductive metal plate. A hole 142 is formed on a middle of the fixed plate for fixing the earth plate 140 to such as a vehicle body with a not-shown screw. A hollow cylinder 143 is formed at an edge of the fixed plate 141. An internal diameter of the cylinder 143 is substantially equal to an outer diameter of the shell 150 so that the shell 150 can be inserted into the cylinder 143. A hole for soldering the earth plate 140 with the shell 150 is formed on the center of the cylinder 143.
The shell 150 is a hollow cylinder made of conductive metal. One opening 151 of the shell 150 is made smaller than an internal diameter of the shell 150. The insulator 160 is received in the shell 150. The insulator 160 includes a first cylinder 161 projecting outward from the opening 151, a second cylinder 162 having an outer diameter being larger than the first cylinder 161 and substantially the same as the inner diameter of the shell 150, and a step 163 interposed between the first and second cylinders 161, 162.
Next, an assembling embodiment of the wire-connecting device 100 will be explained. First, the lead wire 120 is inserted through the shell 150 and the insulator 160 sequentially. Then, the coaxial cable 110 and the lead wire 120 are inserted into the crimp contact 130 so that the core wire 121 and the inner conductor 111 are face to face in the crimp contact 130. Then, the crimp contact 130 is crimped so that the coaxial cable 110 and the lead wire 120 are electrically connected to each other.
After the coaxial cable 110 is inserted into an insulating sleeve 170, the braided wire 112 is folded to cover the sleeve 170. Then, the insulator 160 covers the crimp contact 130, and the shell 150 covers the insulator 160, so that the step 163 contacts an edge of the opening 151. Resultingly, while the first cylinder projects outward from the shell 150, the insulator 160 is received in the shell 150. Simultaneously, while the shell 150 contacts the braided wire 112, the coaxial cable 110 is partially received in the shell 150.
The folded braided wire 112 of the coaxial cable 110 and the insulator 122 of the lead wire 120 are crimped together. Then, the shell 150 is positioned inside the cylinder 143 and solder is inserted into a hole 144 of the cylinder 143, so that the shell 150 and the earth plate 140 are electrically connected to each other. Resultingly, the braided wire 112 of the coaxial cable 110 is connected to the earth plate 140 and grounded to the vehicle body through the earth plate 140. Incidentally, no document has disclosed such a wire-connecting device 100.
In the wire-connecting device 100, folding the braided wire 112 is necessary, or else an unbound end part of the braided wire 112 may be short-circuited, and crimping strength between the coaxial cable 110 and the lead wire 120 may be reduced. Further, the cylinder 143, the shell 150, and the insulator 160 are needed for connecting the coaxial cable 110 and the lead wire 120 to the earth plate 140. Further, soldering process is needed.
Accordingly, an object of the present invention is to provide a wire-connecting device that prevents connecting strength between the coaxial cable 110 and the lead wire 120 from being reduced, and reduces the number of components thereof, and makes connecting and grounding processes easy.